import math
x1, y1, x2, y2 = map(float, raw_input().split())
x, y = x2 - x1, y2 - y1
print math.sqrt(x**2 + y**2) import math math x1, y1, x2, y2 = map(float, raw_input().split()) x1 map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split y1 x2 y2 x, y = x2 - x1, y2 - y1 x x2 - x1 x2 x1 y y2 - y1 y2 y1 print math.sqrt(x**2 + y**2) math.sqrt math sqrt x**2 + y**2 x**2 x 2 y**2 y 2 x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) x2 x1, y1, x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) x1 y2 = map(float, raw_input().split()) map(float, raw_input().split()) y2 y1, x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) y1 y = x2 - x1, y2 - y1 y2 - y1 y x, y = x2 - x1, y2 - y1 x2 - x1 x
import math
x1, y1, x2, y2 = map(float, raw_input().split())
x, y = x2 - x1, y2 - y1
print math.sqrt(x**2 + y**2)